1. Field of the Invention
The present disclosure relates to a disk image acquiring device, and in particular relates to a disk image acquiring device which takes an image of a pattern formed on a surface or a back surface of a disk to acquire a taken image. More specifically, the present disclosure relates to a disk image acquiring device which can also acquire images regarding a plurality of kinds of disks having different diameters easily and securely.
Also, the present disclosure relates to a disk sorting device, and in particular relates to a disk sorting device which takes an image of a pattern formed on a surface or a back surface of a disk to acquire a taken image, compares the taken image with a reference image to discriminate authenticity of the disk, and sorts the disk based upon the discrimination result. More specifically, the present disclosure relates to a disk sorting device which can acquire images regarding a plurality of kinds of disks having different diameters easily and securely to sort the disks.
Incidentally, the disk in this specification has a concept including a coin which is currency, and a medal or a token used in a game machine.
2. Description of Related Art
A device which takes an image of a pattern formed on a surface or a back surface (hereinafter, called “disk surface”) of a disk such as a coin or a medal by an image sensor to make discrimination about authenticity or denomination using the taken image is conventionally proposed, where in particular when an image of a moving disk is taken, such a fact that the disk has arrived at an image-taking position is detected by a timing sensor and an image of the disk is taken based upon a detection output of the timing sensor.
In Japanese Unexamined Patent Application Publication No. 2001-344631 (at, e.g., FIG. 1 and Paragraphs 0019 to 0031), for example, a coin discriminating device which, when a first sensor arranged on an upstream side of an image-taking position in a moving direction of a coin, starts an image-taking operation of an image sensor in advance before a coin arrives at the image-taking position and has detected passage of the coin, and performs irradiation of illumination in a short time to acquire a taken image of a coin surface by the image sensor when a second sensor has detected arrival of the coin at the image-taking position is disclosed.
In Japanese Unexamined Patent Application Publication No. 2002-358551 (at, e.g., FIG. 1 and Paragraphs 0023 to 0027), a coin discriminating device which detects arrival of a leading end of a coin by a coin detecting sensor arranged on a downstream side of an image-taking position in a moving direction of the coin and irradiates a surface of the coin with light in synchronism with detection of the coin detecting sensor to acquire an image of the coin including an outer periphery of the coin by an image sensor is disclosed.
In Japanese Unexamined Patent Application Publication No. 2007-241701 (at, e.g., FIG. 1 and FIG. 2, and Paragraph 0015), a coin image identifying device which detects that light emitted from a light emitting element has been blocked by arrival of a coin by a light receiving element to notify a coin arrival time of an image-taking timing determining means, where the image-taking timing determining means calculates an image-taking timing from the coin arrival time, and an image-taking position of the coin and a coin transportation velocity, and a control part instructs an image-taking means to take an image of the coin at a predetermined position at the image-taking timing is disclosed.
In Japanese Patent No. 3115505 (at, e.g., FIG. 2 and FIG. 3, and Paragraphs 0008 to 0016), a work image-identifying device where a plurality of coin position detectors is arranged at different positions on an upstream side in a coin transport direction and the plurality of coin position detectors are actuated selectively in response to a size of a coin is disclosed.
Now, there is a plurality of kinds of disks having different diameters, such as coins or medals, and a disk image acquiring device which acquires a taken image of a pattern formed on a disk surface is required to acquire a taken image including a whole pattern of a disk surface even regarding a disk having a different diameter. This is because discrimination accuracy lowers if a portion of an image of the pattern is not taken.
In the coin discriminating device described in the above Japanese Unexamined Patent Application Publication No. 2001-344631, there is not any consideration about handling of a coin having a different diameter, where when a diameter of a coin is different, a center position of the coin in an image-taking region is shifted to an upstream side in a moving direction of the coin. Therefore, if an image-taking region is set so as to conform to a small-diameter coin, a pattern of a large-diameter coin having a large shift amount goes over the image-taking region. In other words, there is such a problem that a diameter range of a coin which can be discriminated is small. On the other hand, when the image-taking region is expanded so as to conform to the large-diameter coin, there is such a problem that the image sensor or an illumination device becomes large in size, which results in cost increase and increase in size of the whole device. Though use of a lens having a wide field angle does not require increase in size of the image sensor, increase in size of the illumination device is unavoidable. Further, since the center position varies according to the diameter of the coin, there is also such a problem that because a general method as detecting an outer periphery of a coin to obtain the center position of the coin is applied when the center position of the coin constituting a reference for image discrimination is obtained, a processing time required for image discrimination becomes long.
In the case of the coin discriminating device described in Japanese Unexamined Patent Application Publication No. 2002-358551, though coins different in diameter are assumed, a device imaging a peripheral edge portion of a coin surface is proposed, where there is not any consideration about the case that an image of a whole pattern of a coin surface is acquired. And, since a distal end of the coin is detected by the coin detecting sensor, the center position of the coin in the image-taking region is shifted to an upstream side of the coin in the moving direction of the coin when the diameter of the coin varies. Therefore, there is a problem similar to that in the coin discriminating device described in Japanese Unexamined Patent Application Publication No. 2001-344631.
In the coin image identifying device described in Japanese Unexamined Patent Application Publication No. 2007-241701, since the image-taking timing is calculated from the image-taking position of the coin and the coin transportation velocity, an error occurs easily regarding the image-taking time, so that deviation occurs regarding the center position of the coin to the image-taking region. Therefore, since it is necessary to set the image-taking region large in anticipation of a size corresponding to the error, there is such a problem that the image sensor or the illumination device becomes large in size, which results in cost increase and increase in size of the whole device. Further, since deviation of the center position of the coin occurs, there is also such a problem that because such a general method as detecting an outer periphery of a coin to obtain the center position is applied like the cases described in Japanese Unexamined Patent Application Publication Nos. 2001-344631 and 2002-358551 when the center position of the coin constituting a reference for image discrimination is obtained, a processing time required for image discrimination becomes long.
In the work image-identifying device described in Japanese Patent No. 3115505, since the plurality of coin position detectors corresponding to diameters of coins are required, there is such a problem as increase in cost. Further, since positions and optical axes of the plurality of coin position detectors must be adjusted, there is such a problem that adjusting work becomes complicated.